export default {
  bind(el, binding, vnode) {
    const dialogHeaderEl = el.querySelector('.el-dialog__header')
    const dragDom = el.querySelector('.el-dialog')
    dialogHeaderEl.style.cssText += ';cursor:move;'
    dragDom.style.cssText += ';top:0px;'
    const getStyle = (function () {
      if (window.document.currentStyle) {
        return (dom, attr) => dom.currentStyle[attr]
      } else {
        return (dom, attr) => getComputedStyle(dom, false)[attr]
      }
    })()
    dialogHeaderEl.onmousedown = (e) => {
      // 鼠标按下，计算当前元素距离可视区的距离
      const disX = e.clientX - dialogHeaderEl.offsetLeft
      const disY = e.clientY - dialogHeaderEl.offsetTop
      // console.log('disY', e.clientY, dialogHeaderEl.offsetTop);
      const dragDomWidth = dragDom.offsetWidth
      const dragDomHeight = dragDom.offsetHeight
      const screenWidth = document.body.clientWidth
      const screenHeight = document.body.clientHeight
      const minDragDomLeft = dragDom.offsetLeft
      const maxDragDomLeft = screenWidth - dragDom.offsetLeft - dragDomWidth
      const minDragDomTop = dragDom.offsetTop
      const maxDragDomTop = screenHeight - dragDom.offsetTop - dragDomHeight
      let styL = getStyle(dragDom, 'left')
      let styT = getStyle(dragDom, 'top')

      if (styL.includes('%')) {
        styL = +document.body.clientWidth * (+styL.replace(/\%/g, '') / 100)
        styT = +document.body.clientHeight * (+styT.replace(/\%/g, '') / 100)
      } else {
        styL = +styL.replace(/\px/g, '')
        styT = +styT.replace(/\px/g, '')
      }

      document.onmousemove = function (e) {
        let left = e.clientX - disX
        let top = e.clientY - disY
        if (-(left) > minDragDomLeft) {
          left = -minDragDomLeft
        } else if (left > maxDragDomLeft) {
          left = maxDragDomLeft
        }
        // console.log('top', e.clientY, disY);
        if (-(top) > minDragDomTop) {
          // console.log('minDragDomTop', minDragDomTop);
          top = -minDragDomTop
        } else if (maxDragDomTop > 0 && top > maxDragDomTop) {
          // console.log('maxDragDomTop', maxDragDomTop);
          top = maxDragDomTop
        }
        // console.log('=======', top, styT);
        // 移动当前元素
        dragDom.style.cssText += `;left:${left + styL}px;top:${top + styT}px;`
        vnode.child.$emit('dragDialog')
      }

      document.onmouseup = function (e) {
        document.onmousemove = null
        document.onmouseup = null
      }
    }
  }
}